“Letter between rho and tau”

Lt. ___, communications officer on the original "Star Trek"

N.H.L. tiebreakers

Allow to attack

Epic that ends "Such was the funeral of Hector, tamer of horses"

Prefix with liberal

With 59-Across, "This is beyond a doubt" ... or a punny hint to 24-, 38- and 49-Across

Online chats, in brief

Nickname for Rihanna

Tummy muscles